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Note that this analysis of Swedish registry data suggests a decline in mortality rates among those with Type 1 and Type 2 diabetes.

The decline in mortality among diabetics was less than the decline seen among healthy controls, however.

Risk for all-cause and cardiovascular mortality have declined among patients with diabetes in Sweden, but it is still higher than in the general population, scientists said.

The Swedish trends are consistent with those reported elsewhere in Europe and in the United States, said a research team led by Aidin Rawshani, MD, of the University of Gothenberg in Sweden, reporting in The New England Journal of Medicine.

Among patients with type 2 diabetes (T2D), the all-cause mortality risk declined by 21% over a 10-year period, compared with 31% in matched controls without diabetes. The relative decline in all-cause mortality was 13% greater among the controls (hazard ratio 0.87, 95% CI 0.85-0.89, P<0.001).

Risk of death from cardiovascular disease declined by 46% over 10 years in T2D patients, compared with 50% in matched controls. The relative decline was a significant 6% greater in the control group (HR 0.94, 95% CI 0.90-0.98, P=0.004).

"The changes observed in our study most likely reflect a combination of advances," Rawshani and colleagues wrote. "The increasing emphasis on integrated care of patients with chronic disease, improved patient education in disease management, and advancements in clinical decision-making support have probably reduced the rates of cardiovascular complications among patients with diabetes.

"Perhaps most important, improved management of risk factors such as hypertension, elevated levels of LDL cholesterol and glycated hemoglobin, and macroalbuminuria and the associated higher frequency of treatment with statins and antihypertensive medications have transformed cardiovascular risk reduction," they said.

While these trends are encouraging, it is important to remember that cardiovascular mortality and morbidity risk is still significantly higher for patients with both type 1 and type 2 diabetes than in the general population, Rawshani said in an email to MedPage Today.

"Irrespective of such patterns, there is still an excess overall risk for every cardiovascular outcome analyzed for individuals with T2DM compared with population controls, further underpinning the importance of continued clinical and research aimed at mitigating the residual cardiovascular risk associated with T2DM, and especially mortality risk," he said.

The investigators analyzed data from the Swedish National Diabetes Register, which includes virtually all the patients with diabetes in Sweden. The study included 36,869 adult T1D patients and 457,473 adult T2D patients, along with randomly-chosen non-diabetic controls matched for sex, age, and county of residence. The mean age at entry was 35 for those with T1D and 65 for those with T2D.

At baseline, mean glycated hemoglobin was 8.2% in T1D patients and 7.1% in T2D patients. The mean duration of diabetes was 20 years for T1D patients and 5.7 years for those with T2D. The mean duration of follow up was 11 years for T1D and 6.5 years for T2D patients.

During the study period, mean glycated hemoglobin increased slightly in T1D patients from 66.2 mmol/mol (8.2%) at baseline to 68.4 mmol/mol (8.4%). In T2D patients, it fell from 60.2 to 56.7 mmol/mol (7.7% to 7.3%). In both groups, there were significant decreases in LDL-cholesterol, systolic blood pressure, the prevalence of macroalbuminuria, and prescription rates for statins and antihypertensive drugs.

Risk of hospitalization for cardiovascular disease declined during the study period for patients with both types of diabetes as well as for controls. However, the decline was significantly greater for patients with diabetes compared with controls. For example, hospitalization risk declined by 44% for patients with T2D versus 39% for the controls (P<0.001), the study found.

Limitations of the study include that it did not examine whether changing diagnostic thresholds or admission criteria might have affected hospital admission rates. In addition, "our results are model dependent and could change slightly with different approaches to the data," Rawshani and colleagues said.

"In conclusion, we report a decline in all-cause mortality and the incidence of cardiovascular complications among patients with type 1 diabetes or type 2 diabetes in the Swedish National Diabetes Register," the investigators said. "The reduction in fatal outcomes did not differ significantly between patients with type 1 diabetes and controls, and the reduction in such outcomes was smaller among patients with type 2 diabetes than among controls.

"Although it is difficult to compare event-rate reductions across countries owing to differences in access to care, standards of clinical care, and diagnostic criteria for diabetes, our findings are generally consistent with trends in overall mortality and cardiovascular disease associated with diabetes that have been observed in North America and Europe," they said.

The study was funded by the Swedish Diabetes Foundation, the Swedish Heart and Lung Foundation, the Swedish Research Council, and other organizations.